How to cook the 5G cake: get coverage, capacity and the right services in place

Unlike previous mobile generations, 5G can be deployed in different flavors, this means that not every 5G logo in your device will enable a full 5G experience.

When deploying 5G, operators must tackle different challenges: coverage, capacity and new services introduction. The combination of these will lead to a real 5G experience.

Let’s see how to address each one.

Coverage

To make it simple, the intensity of the cellphone signal decreases with distance and frequency by the inverse square law (or even worse, depending on the scenario). As 5G is standardized over a wide variety of frequency bands, implementing 5G over a low band becomes critical (i.e 5G “logo” every time, everywhere). Here I mean traditional FDD bands that where usually occupied by legacy technologies 2G/3G/4G, which typically spans from 700 MHz to 2600 MHz.

An important choice is whether to dedicate a carrier to 5G 100% of the time or whether to share it with LTE, taking advantage of Dynamic Spectrum Sharing – DSS – feature. This decision could be subject of another post, but in a nutshell any of these will drive coverage but not a big capacity improvement, if any. This is mainly because standardized channels at this frequency rage are rather narrow.

Capacity

In order to understand how 5G will drive capacity, and without being too technical, I always like to remind one of the most important theorems about Information Theory: The Shannon-Hartley theorem, which in short states that in order to increase the capacity, we can either increase the bandwidth of the channel and/or the quality of the connection.

If we want to increase the bandwidth of the channel we need to seek for new frequencies where we can allocate larger channels: the honeypot of this are the millimeter wave frequencies (mmWave), where we can get x20 to x40 more bandwidth than in traditional low frequency bands (400 – 800 Mhz). As mentioned in the previous point, the higher the frequency the lower the coverage, to this will be suitable for hot zones or dense places.

On the other hand, another option could be the centimeter wave frequencies (cmWave), around 3500 MHz, where an operator could get x2 – x5 more bandwidth than in traditional low frequency bands and yet provide decent coverage (40 – 100 MHz). To boost capacity at cmWave, multiuser massive MIMO techniques are implemented. This allows to re-use the same channel among multiple users assuming there is enough spatial diversity. ?

Ideally, a great 5G network should combine cmWave bands with mmWave to take full benefit of 5G capacity. This takes us to the well-known 5G layer cake.

Another variable that plays into the capacity equation is SNR. There are many techniques and functionalities to improve the SNR of a connection. Regarding to deployment, a well-known alternative to improve overall SNR of the system is to densify the network, considering small cells an integral part of the network and not as a complement or separate layer from the macro network.

Services

One of the key differentiators from 5G is its ability to deliver new services to end users. We are not only talking to extreme throughput, but also ultra-low latency, ultra-reliable communications, or network slicing. This will allow, for example, to drive autonomous robots or self-driving cars, do remote latency sensitive operations and many more functionalities.

In particular, mmWave 5G is ideal to deliver not only extreme throughput but also ultra-low latencies. This is due to the very short symbol duration of the mmWave implementation.

On the other hand, the architecture chosen to deploy 5G will play a key role here. Initially most of the 5G networks will be deployed in Non-Stand-Alone mode (NSA), but this architecture won’t be able to offer 5G at its best. It’s clear that to have ultra-low latencies and services slicing, a Stand-Alone (SA) architecture should be targeted. There is an ongoing debate in Latin America about when is the right timing to deploy SA networks. This could be an interesting topic to discuss in another post.

Finally, another promising technology to improve performance and enabling new services is Cloud RAN. In theory, a Cloud RAN implementation in some specific places of the network could boost network efficiency and enable new services that quite tricky to implement over traditional distributed architectures. This is also another interesting topic to be discussed further in another post.

Takeaway: if you want to experience 5G at its best, you should consider three-layered 5G cake, implement network densification using small cells and target a Stand-Alone architecture in the medium term. Also, think about the potentials of a Cloud RAN architecture in some specific places of your network.?

Note: All views expressed on this article are my own and does not necessairly represent the opinion of my current employeer